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MT2000-0200-1 Rev f (10-2007)
DCN0160 13
The following values should be used as starting points:
For Mounting Configuration 1,2,3a and 3b, (direct insertion in tank - no stilling well
applications, no coaxial probes) with the following dielectric constant:
GS THV
≥ 10
2* 1.5*
≥ 3 and < 10
2 1.7
For Mounting Configuration 4,5,6,7,8,9,10a & 10b with the following dielectric
constant: (ground plane probe / installation applications - coaxial probes stilling
well, EC chambers)
GS THV
≥ 10
4 1.0
< 10
4* 1.7*
Assuming the 4 mA point is set toward the bottom end of the probe and that the 20 mA point is set toward the top,
for a given GS setting:
• If THV is set too high the output will either read high or spike high.
• If THV is set too low the output will either read low down to 3.8 mA, spike low, or be in fault high (21mA) or fault
low (3.6mA).
• Adjust THV as needed to obtain a steady output reflecting the actual level over the usable measuring range.
NOTE: If a stable output cannot be obtained, refer to trouble-shooting section or to Appendix F for viewing sensor
signal using an oscilloscope.
4.4.3 Advanced Parameter Settings
• L1O
Level One Offset is used to offset the level output of the transmitter to match the
actual level in your tank or vessel. This offset allows the transmitter to be calibrated
so that the 4mA is equal to a value higher than zero. There are several cases when
Level Offset can be used:
1. To accommodate for a non-measurable length at the bottom of the
probe.
2. To accommodate for the length of the probe being shorter than the ac-
tual length of the tank or vessel due to agitator or other devices near the
bottom.
3. To synchronize two redundant transmitters
4. To allow a zero-based measured variable which is used when an EC
measurement needs to correlate locally to a sight glass. It also simpli-
fies setting the range (from tap to tap)
L1O can be positive or negative and as much as 50% of the sensor trim span (HTP-
LTP). Figure 4.4 shows a typical L1O offset.
Example: If the end of the probe, in Figure 4-4, were 4 inches off the
bottom of the tank the L1O Level Offset would be 4. If the Measured Level
were 21 inches then the local indicator would indicate 25 inches (21 +4) and
the 4-20 mAdc signal would indicate a level of 25 inches. This will provide
local indication and signal of the actual level of 25 inches.
Figure 4.4
L1O
Measured
4.4.2 Threshold Level Parameter (THV) and Gain Setting (GS) (cont’d)
*Factory Default